Dr. Maitreyi Mazumdar is an Assistant in Neurology at Children's Hospital Boston and Instructor in Neurology at Harvard Medical School. The candidate's long-term goal is to develop an independent research career focusing on the role of environmental contaminants in the development of neurological Injury and disease in children. Dr. Mazumdar's interests in this field developed during her Fellowship in neurodevelopmental toxicology, when she became aware of investigations of the effects of environmental arsenic exposure on children in Bangladesh. The proposed Career Development Plan incorporates a multi-disciplinary program designed to provide an intense, closely mentored, patient-oriented research experience, associated with a comprehensively structured didactic curriculum in environmental epidemiology, exposure assessment, advanced biostatistics, and risk assessment. Under the mentorship of Dr. David Christiani, Professor of Environmental Health at the Harvard School of Public Health, the candidate will investigate the effect of prenatal and early childhood arsenic exposure on neurodevelopment of children in Bangladesh, a country with high levels of arsenic contamination in groundwater. This research will examine epidemiological associations of arsenic exposure with measures of neurological development In infants and children, including 1) head circumference, 2) hearing impairment, 3) motor dysfunction, and 4) formal neurocognitive testing. The studies will be conducted in a cohort of 600 infants who are participating in a current study of reproductive health effects of arsenic. Additional children between the ages of 12 and 24 months will also be recruited neurodevelopmental assessment. The superb clinical, research, and teaching facilities of Children's Hospital Boston, Harvard Medical School, and the Harvard School of Public Health will support Dr. Mazumdar in meeting the objectives of her career development and research plans.